The objective of this research is to develop a paradigm by which the childrearing environment can be investigated in detail. Typical rearing functions and parent and child behavior are kept intact by having the participants create their own environment in the laboratory. This is done by having mother and children come to the laboratory, an informal homelike apartment, for a series of half-days. Much of the structure and many of the events in these visits are of the participants own making. Conditions allow and encourage usual routines, behavior, and emotions (eating, playing, learning, disciplining, resting, being happy, angry, upset, etc.). There is also an underlying experimental structure in the sessions standard events (e.g. mother leaves temporarily, mother is made busy in ways that take her attention from the child, a visitor arrives) are introduced as naturally as possible in order to elicit certain classes of response. The procedures, with appropriate changes geared to the age of the children, are repeated at intervals of 1-1/2 years to permit longitudinal study. Normal families and families with psychopathology are the participants. Parents and two siblings (initial ages 2 years and 5 to 8 years) are studied.